In order to transmit and receive communication signals between the respective nodes of a base or parent station, a relay station and a child station in a network, it is necessary to set a path according to the type of network, the transmission quality on a transmission line interconnecting the nodes, and other factors.
Late years, in connection with the progress of communication technologies, developments in networking have been made in various technical fields, and various devices in a house or building are increasingly being connected to networks. The device networking is intended to operate these devices in an organically linked manner and interconnect the network in the building to other networks outside the building in such a manner as to allow the operation of these devices to be instructed from external communication terminals, so as to cope with energy saving, remote control or the like and provide a safe and comfortable living condition. These devices mutually transmit and receive communication signals via networks. As one of communication-signal transmission techniques, there has been known a power-line communication using as a transmission line a distribution line for supplying electric power to these devices (power line). This power-line communication can utilize existing distribution lines to advantageously eliminate the need for laying a new transmission line. Therefore, the power-line communication has additional advantages that an initial installation cost is reduced accordingly, and the deterioration in appearance of a building is avoided.
In a flexible and logical network free from physical factors (VLAN: Virtual Local Area Network), a technique for adding a new user terminal thereto is described in Japanese Patent Laid-Open Publication No. 2002-204247. This publication describes a VLAN information registration system in a VLAN-based network, which comprises: means for allowing a given user-information item required for connecting to the network to be entered at the initiative of a user and then automatically generating user-information management data. The VLAN information registration system further comprises means for converting user registration information to VLAN information, the user registration information being automatically generated by the user-information management data automatic generation means. The VLAN information registration system further comprises means for automatically generating a correspondence table between the VLAN information converted by the conversion means and a MAC (Media Access Control) address of a user terminal. The VLAN information registration system further comprises means for allowing the correspondence table generated by the corresponding-table automatic generation means to be updated in a URT (User Registration Tool) and means for retrieving registered user information and displaying necessary information on an administrator screen. This automatic VLAN information registration system allows a new user terminal to be automatically connected to a network without the need for a network administrator to set VLAN information.
In the power-line communication, the distribution lines are originally intended for power supply, and thereby the transmission quality in each of actual distribution lines varies depending on laying circumstances. This causes difficulties in designing a network in a desktop manner, because the layout position of a relay station cannot be pre-specified in developing the network. Thus, a network has heretofore been developed by measuring the transmission quality on a distribution line at an actual construction site, and locating a relay station thereat if required. Then, in an operation of setting a path to each node in the power-line communication network, the path has been manually set to the node of each station after its construction. Due to these situations, the power-line communication has been required to take a great deal of manual effort and time for the network development and the path setting operation.
Moreover, in the power-line communication, the transmission quality can be dynamically changed due to the variation in load connected with a distribution line. Thus, even if a path is adequately set up, an excellent communication cannot be always maintained.
The technique described in the aforementioned publication is for use in a higher layer than a data link layer, wherein a user who intends to connect to a network is required to enter user information from a new user terminal.
In view of the above problems, it is therefore an object of the present invention to provide a path setting method allowing a path to be automatically set up. It is another object of the present invention to provide a network, relay station and parent station employing this path setting method.